WO2020188215A1 - Braided shield of a flat harness - Google Patents

Braided shield of a flat harness Download PDF

Info

Publication number
WO2020188215A1
WO2020188215A1 PCT/FR2020/050565 FR2020050565W WO2020188215A1 WO 2020188215 A1 WO2020188215 A1 WO 2020188215A1 FR 2020050565 W FR2020050565 W FR 2020050565W WO 2020188215 A1 WO2020188215 A1 WO 2020188215A1
Authority
WO
WIPO (PCT)
Prior art keywords
braiding
flat
harness
faces
braided shield
Prior art date
Application number
PCT/FR2020/050565
Other languages
French (fr)
Inventor
Jérôme GENOULAZ
Original Assignee
Safran Electrical & Power
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Safran Electrical & Power filed Critical Safran Electrical & Power
Publication of WO2020188215A1 publication Critical patent/WO2020188215A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B7/00—Insulated conductors or cables characterised by their form
    • H01B7/08—Flat or ribbon cables
    • H01B7/0861—Flat or ribbon cables comprising one or more screens
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/22—Sheathing; Armouring; Screening; Applying other protective layers
    • H01B13/26—Sheathing; Armouring; Screening; Applying other protective layers by winding, braiding or longitudinal lapping
    • H01B13/2606—Sheathing; Armouring; Screening; Applying other protective layers by winding, braiding or longitudinal lapping by braiding

Definitions

  • the present invention relates to the field of flat electrical harnesses and more particularly to the aeronautical field.
  • Aeronautics is constantly seeking to reduce fuel consumption. This saving can be achieved by reducing the weight of the aircraft and / or by increasing the performance of the propulsion system.
  • a propulsion system of the UHBR type "Ultra Higb Bypass Ratio" This system makes it possible to increase the dilution ratio between the primary flow and the secondary flow of the aircraft engine. As the areas allowing the passage of engine air flows are greater, this leaves less room for the equipment and their electrical connections placed in the nacelle part, that is to say on the periphery of the engine.
  • the use of flat rather than circular electrical harnesses would make it possible to route the electrical connections in areas of low thickness.
  • EMC electromagnetic compatibility
  • FIG. 9 is a graph illustrating the transfer impedance of a braided shield on a flat harness but mechanically dimensioned in a manner conventionally used on a round harness.
  • the graph illustrates a curve C1 representing the modulus of the overall transfer impedance of the braided shield as a function of the frequency.
  • Curve S represents the upper threshold of the transfer impedance modulus as a function of frequency and according to aeronautical specifications. This graph shows that the curve C1 exceeds the specification threshold S, therefore indicating insufficient electromagnetic performance.
  • the object of the present invention is to provide a flat harness shielding overcoming the aforementioned drawbacks, ensuring very good electromagnetic protection and therefore high efficiency against electromagnetic attacks from the environment.
  • the present invention is defined by a flat harness for transmitting electrical signals, comprising a braided shield delimited by almost flattened faces comprising two flat faces of predetermined width and two slices of predetermined thickness, each of said faces comprising a different braiding pattern.
  • the braiding pattern on each flat face being defined by a first braiding angle ai and a first filling coefficient Kr L
  • the braiding pattern on each slice being defined by a second braiding angle a e and a second filling coefficient K re
  • the first braiding angle "L being chosen for be between approximately 40 ° and 45 °
  • the second filling coefficient K re being chosen to be approximately equal to 1 and the other parameters of the braided shielding resulting from the following equations:
  • a flat harness is understood to mean a harness whose section has the shape of a flattened ovoid, a flattened ellipse or a quasi-rectangle, the angles of which may be rounded.
  • the section of the flat harness advantageously has a shape without a sharp edge to delimit the two flat faces and the two edges.
  • Modulating the patterns according to the perimeter of the harness makes it possible to take advantage of the flat shape of the harness so that the different partial transfer impedances at least partially compensate each other, making it possible to minimize the overall transfer impedance of the harness.
  • This ensures electromagnetic compatibility between the harness and neighboring equipment while protecting the electrical signals transmitted by the harness against electromagnetic attacks (strong fields and lightning) from the environment.
  • the ratio between the thickness of the harness and its width known as the form factor, is between approximately 1 and 1/6 and preferably between 1 ⁇ 2 and
  • the harness can be routed in very narrow areas or spaces.
  • the braiding angle on the flat face as well as the filling coefficient on the edge of the braided shielding are selected so that the sum of the partial transfer impedance of a flat face and the partial transfer impedance of a slice of the braided shield is smaller than the value of each of said partial transfer impedances taken individually.
  • the first braiding angle on the flat face of the braided shielding is chosen to be between approximately 40 ° and 45 ° and preferably closer to 45 °
  • the second filling coefficient on the edge of the braided shielding is chosen to be approximately equal to 1.
  • the phase opposition between the partial transfer impedances relating to the flat faces and the partial transfer impedances relating to the slices is produced in a predetermined frequency band of interest.
  • This frequency band is a function of the phenomena against which the system is electromagnetically protected.
  • the flattened faces are almost arched. More particularly, it is the edges that are arched.
  • the two sections are formed by the semi-circle of the section of the end cables.
  • the invention also relates to an electrical harness comprising at least one flat portion, called a flat harness according to the above characteristics,
  • the electrical harness comprises a round harness interposed on at least one predetermined portion by a flat harness, said flat harness being configured to pass through areas having sections smaller than the section of the round harness.
  • the invention also relates to an aircraft electrical system comprising at least one electrical harness according to any one of the preceding characteristics.
  • the invention also relates to a method of manufacturing a flat harness intended to transmit electrical signals, comprising the use of a braiding machine to form a braided shield delimited by almost flattened faces comprising two flat faces of predetermined width and two slices of predetermined thickness, each of said faces comprising a braiding pattern different from those of the two adjacent faces, the braiding pattern on each flat face being defined by a first braiding angle 3 ⁇ 4 and a first filling coefficient K rL , the braiding pattern on each slice being defined by a second braiding angle a e and a second filling coefficient K re , the first braiding angle ⁇ L being chosen to be between about 40 ° and 45 °, the second filling coefficient K re being chosen to be approximately equal to 1 and the other parameters of the braided shield deriving from the following equations;
  • a determined number of coils is used, chosen from the following numbers of coils: 16, 24, 32, 48, and 64.
  • a number of strands per spindle of between 3 and 16 is used.
  • the diameter of the strands can be selected from the following diameters: 0.08 mm, 0.10 mm, 0.127 mm , 0.15 mm, and 0.20 mm.
  • FIG. IDj schematically illustrate a braided shielding of a flat harness, according to one embodiment of the invention
  • FIG. 2 very schematically illustrates a method of braiding on a flat harness, according to one embodiment of the invention
  • FIG. 3 is a graph representing the flattening of one of the strands of the braid over a length of one step, according to the method of FIG. 2;
  • FIG. 5 are graphs illustrating relationships between braiding angles and a fill coefficient, according to the present invention.
  • FIG. 6 is a graph representing the relationship between the phase of the transfer impedance and the filling coefficient of the braided shielding as well as the braiding angle, according to the invention.
  • FIG. 7 is a graph representing first and second transfer impedances in a complex plane, relating respectively to a flat face and a slice of the rectangular braided shielding, according to the invention
  • FIG. 8 is a graph illustrating the transfer impedance of a braided shield according to a preferred embodiment of the invention.
  • FIG. 9 is a graph illustrating the transfer impedance of a braided shield, according to a braiding technique of the state of the art.
  • the concept underlying the invention consists in producing a braided shield on a flat harness by appropriately taking advantage of the asymmetry of the patterns during the braiding to reduce the overall transfer impedance of the shield.
  • the present invention applies generally to any type of flat harness and in particular to those which can be used in fields with high safety requirements such as for example in the aeronautical field.
  • Figs. IA - 1D very schematically illustrate a braided shield of a flat harness according to one embodiment of the invention. For simplicity and clarity, the diagrams are not shown to scale.
  • the flat harness 1 comprises a braided metallic shielding 3 delimited by quasi-flattened faces 31, 33 each of which comprises an elementary braiding pattern 35, 37 different from those of the two adjacent faces.
  • quasi-flattened faces is understood to mean faces that are extrinsically flat or extrinsically arcuate in a slight curvature.
  • the flat harness may be of flattened elliptical, flattened ovoidal, or almost flattened rectangular shape. The faces of the flat harness may thus not be delimited by sharp or marked edges.
  • the harness 1 has four faces (shown in the drawing in an almost rectangular manner) and the different braiding patterns 35, 37 are configured so that the braided shield has a minimum transfer impedance.
  • the faces of the flat harness delimiting the braided armor 3 comprise two flat faces 31 of predetermined width and two slices 33 of predetermined thickness.
  • the ratio between the thickness e of the harness 1 and its width L, called the form factor, is advantageously between approximately 1 and 1/6 and preferably between 1 ⁇ 2 and 3 ⁇ 4.
  • the flat faces 31 have a first braiding pattern 35 while the slices 33 have a second braiding pattern 37 different from the first pattern 35,
  • the electromagnetic performance of the braided shield 3 is given by its transfer impedance which can be evaluated from the geometric and material characteristics of the shield. These characteristics include the number m of coils or spindles 38 used to carry out the braiding, the number n of elementary strands 39 per spindle 38, the diameter d of an elementary strand 39, the braiding angle a with respect to the axis 11 of the harness 1 or the pitch p (see also Fig, 2), and the resistivity p of the material used for the strands 39,
  • Figs, IC and 1D very schematically illustrate a section of a flat harness, according to one embodiment of the invention
  • FIG, IC shows the section of a harness pla comprising six cables 35 placed side by side.
  • the cables 35 all have the same radius R,
  • the width L of the flat faces 31 is of the order of 6 * 2 * R and the thickness e of the harness 1 is of the order of 2 * R.
  • the form factor ie, the ratio between the thickness e of the harness 1 and its width L
  • the edges 33 are arched according to a radius of curvature greater than or equal to R.
  • Fig. 1D shows the section of a flat harness comprising twelve cables 35 placed side by side on two levels, Each level comprises six cables 35 of the same radius R.
  • the width L of the flat faces 31 is always of the order of 12R while the thickness e of the slices 33 is of the order of 4R.
  • the form factor is then of the order of 1/3 and the slices 33 are less curved than in the example of FIG. IC.
  • FIG, 2 very schematically illustrates a method of braiding on a flat harness according to one embodiment of the invention.
  • the braided shielding 3 is produced using a braiding machine 5 in which the coils 51 are each provided with elementary metallic strands 39 (for example, copper) assembled in a spindle. These coils 51 perform several rotations on a turntable 53 and deliver bundles of metal strands 39, For the sake of simplification, only four individual strands 39 delivered respectively by four coils 51 are shown in FIG, 2. It will be noted that depending on the type of braided shield, the number of coils can be 16, 24, 32, 48, 64, etc., This number is even because half of the coils 51 rotate in one direction while the other half rotate in the opposite direction so that the crossings of the strands 39 form the intersections of the braids. On the other hand, the number of strands per spindle can be between 3 and 16. Furthermore, the diameter of a strand 39 can be equal to 0.08 mm, 0.10 mm, 0.127 mm, 0.15 mm, or 0.20 mm.
  • a quarter turn of the coil will correspond to a quarter of a pitch p / 4 as shown in the example of FIG. 2.
  • a braiding pitch p is defined by a complete turn of a spindle or of a strand 39 around the harness 1. The pitch p therefore also corresponds to a complete rotation of a coil 51 in the machine braiding 5.
  • the difference in size between the width L and the thickness e of the harness 1 produces a braiding angle on the flat faces 31 that differs from that on the edges 33 of the harness 3 .
  • FIG. 3 is a graph representing the flattening of one of the strands of the braid over a length of one step, according to the method of FIG. 2,
  • the perimeter of the flat harness 1 is shown on the abscissa and the length of a pitch p is shown on the ordinate.
  • the harness 1 is sufficiently small compared to the plate 53 of the coils 51, the strand 39 makes approximately a quarter of a pitch “p / 4” on the flat face 31 and approximately a quarter of a pitch “p / 4” on the slice 33 of the flat harness 1.
  • the braiding angle a. s on the wafer 33 of average thickness e m is smaller than the braiding angle ai . on the flat face 31 of average width L m .
  • these braiding angles a e and ai . are related by the following equation;
  • the average width L and the average thickness e m of the braided armor 3 are respectively equal to the width L and the thickness e of the flat harness 1 each increased by twice the diameter d of an elementary strand 39 (see Figs. IA , IB):
  • the transfer impedance Z of the braided shield 3 consists of a resistive component R t and of an inductive component L t .
  • the resistive component R t reflects the electrical resistance of the strands 39 of the braid on which the diffusion phenomenon is superimposed. It can be defined as the sum of twice the resistive component on the flat face 31 and twice the resistive component on the wafer 33. It can then be calculated by taking the average of the resistive component R ti. of a round braiding having the characteristics of the flat face 31 and of the resistive component R te of a round braiding having the characteristics of the edge 33. We then obtain:
  • the inductive component L t depends on the braiding angles and can be defined as the average of the inductive components L tL and L te on the edges 33 and flat faces 31 of the braided shield 3. It will also be noted that the number of patterns base 35 is identical to the number of base patterns 37 on the different faces 31, 33 of the braided shielding 3, and as the inductance is weighted by the number of base patterns, then the inductive component U is defined by:
  • the present invention solves this problem by configuring the braiding patterns 35, 37 on the slices 33 and flat faces 31 of the braided shield 3 so that the latter can have a minimum transfer impedance.
  • This modulation of the braiding patterns 35, 37 is achieved by varying the braiding angles as a function of the filling coefficients on each of the faces 31, 33 of the braided shield 3.
  • the filling coefficient K (or covering) represents the ratio between the area covered by the material of the braid (Le, the strands) and the total area considering only the strands placed in the same direction of rotation around the harness. This load factor can be expressed as a percentage. Note that this coverage coefficient is different from the optical coverage coefficient which takes into account all the strands placed in both directions. The latter is therefore greater than the recovery coefficient,
  • the braiding angle a s on a slice 33 and the braiding angle CII on a flat face 31 are connected to the filling coefficient K re on a wafer 33 and to the filling coefficient Kri. on a flat face 31 according to the following equation:
  • These parameters consist of a first braiding angle ⁇ 3 ⁇ 4 and a first filling coefficient K ri on the flat face 31 of the flat harness 1, as well as a second angle ⁇ . s of braiding and a second filling coefficient K re on the edge 33 of the flat harness 1.
  • the first 3 ⁇ 4 and second a e braiding angles as well as the first K rL and second K re filling coefficients are determined so that the partial transfer impedances relating to the flat faces 31 of the harness 1 are at least partially in phase opposition with respect to the partial transfer impedances relating to the sections 33 of the harness 1,
  • the phase opposition between the partial transfer impedances relating to the flat faces (31) and the partial transfer impedances relating to the sections (33 ) is performed in a predetermined frequency band of interest (see Fig. 9).
  • a preferred embodiment of the invention consists in fixing the magnitudes of two parameters and in varying the other parameters so as to minimize the transfer impedance.
  • the two most appropriate parameters to be set are chosen as a function of the relationships between the various parameters.
  • Figs. 4 and 5 are graphs illustrating the relationships between braiding angles and filling coefficient according to different shapes of the harness.
  • FIG. 4 illustrates the relationship between the angle a e of braiding on a wafer 33 and the angle a i . braiding on a flat face 31 according to different form factors F1-F4 of the flat harness 1.
  • the braiding angle 3 ⁇ 4 on the flat face 31 of the harness 1 is limited to between 20 ° and 45 °. Indeed, beyond 45 °, the braiding becomes dense and the weight of the braided shielding 3 increases for a lower low frequency performance. On the other hand, for angles smaller than 20 °, there will be less good mechanical strength.
  • FIG. 5 illustrates the relationship between the filling coefficient K ri and the braiding angle ai on a flat face 31 according to different form factors F1-F4 of the flat harness 1 for a value of Kre equal to 1.
  • the braiding angle ⁇ 1 on the flat face 31 of the flat harness 1 is advantageously selected between approximately 40 ° and 45 ° and preferably closer to 45 °.
  • the second filling coefficient K rs on the edge 33 of the harness 1 is chosen to be close to unity. This filling coefficient close to ⁇ 'can be obtained by adjusting the diameter of the strands 39, the number of strands per spindle 38 and the number of spindles. This makes it possible according to the above equations to have an optimum filling coefficient of about 0.6 on the flat faces.
  • FIG. 6 is a graph showing the relationship between the phase of the transfer impedance and the fill coefficient of the braided shield as well as the braiding angle.
  • the filling coefficient K is represented on the ordinate between the values 0.3 and 1.
  • the value 1 indicates that the space of the harness 1 is entirely covered by the strands 39 of the same direction of rotation.
  • the braiding angle a on one side of the braided shield 3 is shown on the abscissa between the values 15 ° and 70 °.
  • the graph is subdivided into several regions according to the value of the phase f of the transfer impedance Z.
  • This graph shows that a judicious choice of the configurations of the braided shielding 3 makes it possible to obtain two braiding patterns 35, 37, of which the impedances transfer have opposite phases.
  • this graph shows that for a braiding angle Q in a zone B1 between 40 ° and 45 °, we obtain a filling coefficient K rt around 0.6 (ie between 0.5 and 0.7) and a phase fi equal to 90 ° of the first transfer impedance Zi (ie partial transfer impedance on the flat face 31).
  • FIG. 7 is a graph representing the first and second transfer impedances 3 ⁇ 4 and Z e in a plane of complex numbers, relating respectively to a flat face and a slice of the rectangular braided shielding, according to the invention.
  • the modulus Z of the sum of the first and second transfer impedances Zi and Z e is thus less than the modulus of each of the partial transfer impedances Zi and Z e taken individually.
  • Fig. 8 is a graph illustrating the transfer impedance of a braided shield according to a preferred embodiment of the invention. This graph is produced by measuring the transfer impedance independently on a flat face, on a wafer and on the perimeter of the braided shield on a flat harness. To measure the transfer impedance on one side, a current is circulated between the shielding and a wire placed above the side of interest and the coupling voltage between the wire and the shielding is measured using the technique known as injection wire. In addition, to measure the overall transfer impedance, we use the same method but, this time, on a fi! spiraled around the perimeter of the armor.
  • the graph represents the modulus of the transfer impedance according to the invention as a function of frequency.
  • Curve Cil represents the modulus of the transfer impedance on a flat face 31 of the braided shield 3 while the curve C12 represents the modulus of the impedance on a slice 33 of the braided shield 3.
  • the curve C13 represents the modulus of the total impedance of the braided shield 3.
  • the curve C13 is situated well below the curves C11 and C12, reflecting the fact that the partial transfer impedances have opposite phases.
  • the S curve represents the upper threshold of the transfer impedance modulus according to certain aeronautical specifications. This graph shows that the curve C13 representing the modulus of the overall impedance of the braided shield is well below the threshold S of the specifications, therefore indicating very good electromagnetic performance.
  • the present invention makes it possible to cleverly choose the parameters of the shielding: number of spindles, number of strands per spindle, diameters of the strands and one of the braiding angles, so as to obtain Partial impedances in phase opposition between each face and an adjacent face.
  • This has the technical effect of advantageously minimizing the overall transfer impedance of the braided shield. It will be noted that only two of the four parameters comprising the braiding angles and the filling coefficients of two adjacent faces are selected because the other two are imposed by the geometry and the configuration of the flat harness according to the equations described above.
  • the flat harness according to the invention can be produced over only part of the length of a round harness.
  • the electrical harness can be round over a large part of its length and then flattened over certain portions to allow the harness to pass through confined areas having sections smaller than the section of the round harness.
  • the invention also relates to an aircraft electrical system comprising partially flattened round harnesses (i.e. comprising flat harnesses on certain portions) or flat harnesses over all their lengths.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Insulated Conductors (AREA)
  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

The invention relates to a flat harness intended to transmit electrical signals, having a braided shield (3) delimited by more or less flattened faces (31, 33) comprising two flat faces (31) of predetermined width and two edges (33) of predetermined thickness, each of said faces (31, 33) having a different braiding pattern (35, 37) from those of the two adjacent faces, the braiding pattern (35) on each flat face (31) being defined by a first braiding angle and a first fill factor, the braiding pattern (37) on each edge (33) being defined by a second braiding angle and a second fill factor, and the first and second braiding angles and the first and second fill factors being configured such that the partial transfer impedances relative to the flat faces (31) of the braided shield (3) are at least partially in phase opposition with respect to the partial transfer impedances relative to the edges (33) of the braided shield (3).

Description

DESCRIPTION DESCRIPTION
TITRE : BLINDAGE TRESSÉ D'UN HARNAIS PLAT TITLE: BRAIDED ARMOR OF A FLAT HARNESS
Domaine technique Technical area
La présente invention concerne le domaine des harnais électriques plats et plus particulièrement, dans ie domaine aéronautique. The present invention relates to the field of flat electrical harnesses and more particularly to the aeronautical field.
Etat de la technique antérieure State of the prior art
L'aéronautique est en constante recherche de diminution de consommation de carburant. Cette économie peut se faire en réduisant la masse de l'aéronef et/ou en augmentant la performance du système propulsif. Pour augmenter le rendement des turbopropuiseurs, une des solutions envisagée est l'utilisation de système propulsif de type UHBR « Ultra Higb Bypass Ratio ». Ce système permet d'augmenter le taux de dilution entre le flux primaire et le flux secondaire du moteur d’aéronef. Les zones permettant le passage des flux d'air moteur étant plus importantes, cela laisse moins de place pour les équipements et leurs liaisons électriques placés dans la partie nacelle, c'est-à-dire en périphérie du moteur. Dans ce contexte, l'utilisation de harnais électriques plats plutôt que circulaires permettrait de faire cheminer les liaisons électriques dans des zones de faible épaisseur. Pour assurer une compatibilité électromagnétique (CEM), entre le harnais et les équipements au sein du turbopropuiseur ainsi qu'une protection contre les agressions externes {champs forts et foudre), ie harnais doit être blindé. Aeronautics is constantly seeking to reduce fuel consumption. This saving can be achieved by reducing the weight of the aircraft and / or by increasing the performance of the propulsion system. To increase the efficiency of turboprop aircraft, one of the solutions envisaged is the use of a propulsion system of the UHBR type "Ultra Higb Bypass Ratio". This system makes it possible to increase the dilution ratio between the primary flow and the secondary flow of the aircraft engine. As the areas allowing the passage of engine air flows are greater, this leaves less room for the equipment and their electrical connections placed in the nacelle part, that is to say on the periphery of the engine. In this context, the use of flat rather than circular electrical harnesses would make it possible to route the electrical connections in areas of low thickness. To ensure electromagnetic compatibility (EMC) between the harness and the equipment within the turboprop as well as protection against external attacks (strong fields and lightning), the harness must be shielded.
Actuellement, il existe des blindages de câbles plats réalisés à base de rubans métalliques ou rubans polyester métallisés que l'on retrouve dans le domaine de la téléphonie ou l'informatique. Toutefois, ces blindages ne présentent pas une protection électromagnétique suffisante pour être utilisés dans ie domaine aéronautique car iis n'ont pas les performances requises pour se protéger contre la foudre ou les émissions électromagnétiques de certains types d’antennes ou de liaisons filaires. Currently, there are flat cable shields made from metallic tapes or metallized polyester tapes found in the field of telephony or data processing. However, these shields do not have sufficient electromagnetic protection to be used in the aeronautical field because they do not have the performance required to protect against lightning or electromagnetic emissions from certain types of antennas or wire links.
Dans le domaine aéronautique, il existe des blindages à base de brins conducteurs tressés autour des harnais, Un exemple de ce genre de blindage est décrit dans le brevet WO 1996027197 de la demanderesse. Ces blindages assurent une bonne compatibilité électromagnétique avec les équipements du moteur et sont très efficaces contre les agressions électromagnétiques de l'environnement. In the aeronautical field, there are shields based on conductive strands braided around the harnesses. An example of this type of shielding is described in patent WO 1996027197 of the applicant. These shields ensure good compatibility electromagnetic with engine equipment and are very effective against electromagnetic attacks from the environment.
Toutefois, ces blindages sont utilisés pour des harnais ronds et leur configuration de tressage sur des harnais plats n'entraîne pas une bonne performance électromagnétique. En effet, le harnais plat impose une certaine configuration de tressage très différente de celle sur un harnais rond. Cette configuration est régie par des relations mécaniques entre la géométrie du tressage sur la partie plate et l’épaisseur du harnais plat. On notera que la performance électromagnétique peut être évaluée en mesurant l'impédance de transfert du blindage tressé. However, these shields are used for round harnesses and their braiding configuration on flat harnesses does not result in good electromagnetic performance. This is because the flat harness imposes a certain braiding configuration that is very different from that on a round harness. This configuration is governed by mechanical relationships between the geometry of the braiding on the flat part and the thickness of the flat harness. Note that the electromagnetic performance can be evaluated by measuring the transfer impedance of the braided shield.
En effet, la Fig. 9 est un graphe illustrant l'impédance de transfert d'un blindage tressé sur un harnais plat mais dimensionné mécaniquement de manière classiquement utilisée sur un harnais rond. Le graphe illustre une courbe Cl représentant le module de l'impédance de transfert globale du blindage tressé en fonction de la fréquence. La courbe S représente le seuil supérieur du module de l'impédance de transfert en fonction de la fréquence et selon des spécifications aéronautiques. Ce graphe montre que la courbe Cl dépasse le seuil S de spécification indiquant par conséquent une performance électromagnétique insuffisante. Indeed, FIG. 9 is a graph illustrating the transfer impedance of a braided shield on a flat harness but mechanically dimensioned in a manner conventionally used on a round harness. The graph illustrates a curve C1 representing the modulus of the overall transfer impedance of the braided shield as a function of the frequency. Curve S represents the upper threshold of the transfer impedance modulus as a function of frequency and according to aeronautical specifications. This graph shows that the curve C1 exceeds the specification threshold S, therefore indicating insufficient electromagnetic performance.
L'objet de la présente invention est de proposer un blindage de harnais plat remédiant aux inconvénients précités, assurant une très bonne protection électromagnétique et par conséquent, une grande efficacité contre les agressions électromagnétiques de l'environnement. The object of the present invention is to provide a flat harness shielding overcoming the aforementioned drawbacks, ensuring very good electromagnetic protection and therefore high efficiency against electromagnetic attacks from the environment.
Présentation de l'invention Presentation of the invention
La présente invention est définie par un harnais plat destiné à transmettre des signaux électriques, comportant un blindage tressé délimité par des faces quasi aplaties comportant deux faces plates de largeur prédéterminée et deux tranches d’épaisseur prédéterminée, chacune desdites faces comportant un motif de tressage différent de ceux des deux faces adjacentes, le motif de tressage sur chaque face plate étant défini par un premier angle de tressage ai et un premier coefficient de remplissage KrL, le motif de tressage sur chaque tranche étant défini par un deuxième angle de tressage ae et un deuxième coefficient de remplissage Kre, le premier angle de tressage «L étant choisi pour être compris entre environ 40° et 45°, le deuxième coefficient de remplissage Kre étant choisi pour être d'environ égal à 1 et les autres paramètres du blindage tressé découlant des équations suivantes: The present invention is defined by a flat harness for transmitting electrical signals, comprising a braided shield delimited by almost flattened faces comprising two flat faces of predetermined width and two slices of predetermined thickness, each of said faces comprising a different braiding pattern. those of the two adjacent faces, the braiding pattern on each flat face being defined by a first braiding angle ai and a first filling coefficient Kr L , the braiding pattern on each slice being defined by a second braiding angle a e and a second filling coefficient K re , the first braiding angle "L being chosen for be between approximately 40 ° and 45 °, the second filling coefficient K re being chosen to be approximately equal to 1 and the other parameters of the braided shielding resulting from the following equations:
Lm tan(ae) = em tan (¾) et KrL cos (¾) = Kre cos(ae) configurant ainsi les premier et deuxième angles de tressage ainsi que les premier et deuxième coefficients de remplissage pour que les impédances de transfert partielles relatives aux faces plates du blindage tressé soient au moins partiellement en opposition de phase par rapport aux impédances de transfert partielles relatives aux tranches du blindage tressé. L m tan (a e ) = e m tan (¾) and K rL cos (¾) = K re cos (a e ) thus configuring the first and second braiding angles as well as the first and second filling coefficients so that the Partial transfer impedances relating to the flat faces of the braided shield are at least partially out of phase with respect to the partial transfer impedances relating to the edges of the braided shield.
On entend par un harnais plat un harnais dont la section présente une forme d'ovoïde aplati, d'ellipse aplatie ou de quasi rectangle dont les angles peuvent être arrondis. Ainsi, la section du harnais plat présente avantageusement une forme sans arrête franche pour délimiter les deux faces plates et les deux tranches. A flat harness is understood to mean a harness whose section has the shape of a flattened ovoid, a flattened ellipse or a quasi-rectangle, the angles of which may be rounded. Thus, the section of the flat harness advantageously has a shape without a sharp edge to delimit the two flat faces and the two edges.
La modulation des motifs selon le périmètre du harnais permet de prendre avantage de la forme plate du harnais de sorte que les différentes Impédances de transfert partielles se compensent au moins en partie, permettant de minimiser l'impédance de transfert globale du harnais. Ceci assure une compatibilité électromagnétique entre le harnais et les équipements voisins tout en protégeant les signaux électriques transmis par le harnais contre les agressions électromagnétiques (champs forts et foudre) de l'environnement. Avantageusement, le rapport entre l'épaisseur du harnais et sa largeur, dit facteur de forme, est compris entre environ 1 et 1/6 et de préférence entre ½ et
Figure imgf000005_0001
Modulating the patterns according to the perimeter of the harness makes it possible to take advantage of the flat shape of the harness so that the different partial transfer impedances at least partially compensate each other, making it possible to minimize the overall transfer impedance of the harness. This ensures electromagnetic compatibility between the harness and neighboring equipment while protecting the electrical signals transmitted by the harness against electromagnetic attacks (strong fields and lightning) from the environment. Advantageously, the ratio between the thickness of the harness and its width, known as the form factor, is between approximately 1 and 1/6 and preferably between ½ and
Figure imgf000005_0001
En ayant des tranches de faible épaisseur, le harnais peut être cheminé dans des zones ou espaces très étroits. By having thin slices, the harness can be routed in very narrow areas or spaces.
Avantageusement, l'angle de tressage sur la face plate ainsi que le coefficient de remplissage sur la tranche du blindage tressé sont sélectionnés pour que la somme de l’impédance de transfert partielle d'une face plate et l'Impédance de transfert partielle d'une tranche du blindage tressé soit plus petite que la valeur de chacune desdites impédances de transfert partielles prises individuellement. Selon un mode de réalisation de la présente invention, le premier angle de tressage sur la face plate du blindage tressé est choisi pour être compris entre environ 40° et 45° et de préférence plus proche de 45°, Advantageously, the braiding angle on the flat face as well as the filling coefficient on the edge of the braided shielding are selected so that the sum of the partial transfer impedance of a flat face and the partial transfer impedance of a slice of the braided shield is smaller than the value of each of said partial transfer impedances taken individually. According to an embodiment of the present invention, the first braiding angle on the flat face of the braided shielding is chosen to be between approximately 40 ° and 45 ° and preferably closer to 45 °,
Ceci permet d'obtenir un angle de tressage sur la tranche supérieure à 10° satisfaisant un compromis entre une tenue mécanique impactée par l'angle faible de la tranche et une minimisation du poids du harnais impacté par l'angle élevé de la face plate. This makes it possible to obtain a braiding angle on the edge greater than 10 ° satisfying a compromise between a mechanical strength impacted by the low angle of the edge and a minimization of the weight of the harness impacted by the high angle of the flat face.
Avantageusement, le deuxième coefficient de remplissage sur la tranche du blindage tressé est choisi pour être d'environ égal à 1. Advantageously, the second filling coefficient on the edge of the braided shielding is chosen to be approximately equal to 1.
Ceci permet d'avoir un coefficient de remplissage optimal (environ 0,6) sur les faces plates. Avantageusement, l'opposition de phase entre les impédances de transfert partielles relatives aux faces plates et les impédances de transfert partielles relatives aux tranches est réalisée dans une bande de fréquence d'intérêt prédéterminée. Cette bande de fréquence est fonction des phénomènes contre lesquels le système est électro- magnétiquement protégé. This makes it possible to have an optimal filling coefficient (approximately 0.6) on the flat faces. Advantageously, the phase opposition between the partial transfer impedances relating to the flat faces and the partial transfer impedances relating to the slices is produced in a predetermined frequency band of interest. This frequency band is a function of the phenomena against which the system is electromagnetically protected.
Selon un mode de réalisation particulier de la présente invention, les faces aplaties sont quasiment arquées. Plus particulièrement, ce sont les tranches qui sont arquées. Par exemple, pour un harnais constitué de quatre câbles alignés (rapport ¾) dans un même pian, les deux tranches sont constituées par le demi-cercle de la section des câbles d'extrémité. According to a particular embodiment of the present invention, the flattened faces are almost arched. More particularly, it is the edges that are arched. For example, for a harness made up of four aligned cables (ratio ¾) in the same plan, the two sections are formed by the semi-circle of the section of the end cables.
L'invention concerne également un harnais électrique comportant au moins une portion plate, dite harnais plat selon les caractéristiques ci-dessus, The invention also relates to an electrical harness comprising at least one flat portion, called a flat harness according to the above characteristics,
Avantageusement, le harnais électrique comporte un harnais rond intercalé sur au moins une portion prédéterminée par un harnais plat, ledit harnais plat étant configuré pour passer dans des zones présentant des sections inférieures à la section du harnais rond. L'invention vise également un système électrique d'aéronef comportant au moins un harnais électrique selon l'une quelconque des caractéristiques précédentes. Advantageously, the electrical harness comprises a round harness interposed on at least one predetermined portion by a flat harness, said flat harness being configured to pass through areas having sections smaller than the section of the round harness. The invention also relates to an aircraft electrical system comprising at least one electrical harness according to any one of the preceding characteristics.
Ceci permet de faire cheminer le harnais électrique dans des zones de faible épaisseur tout en assurant une compatibilité électromagnétique entre le harnais et les équipements au sein du moteur et une protection contre les agressions externes (champs forts et foudre). L’invention vise aussi un procédé de fabrication d'un harnais plat destiné à transmettre des signaux électriques, comportant l'utilisation d'une machine à tresser pour former un blindage tressé délimité par des faces quasi aplaties comportant deux faces plates de largeur prédéterminée et deux tranches d'épaisseur prédéterminée, chacune desdites faces comportant un motif de tressage différent de ceux des deux faces adjacentes, le motif de tressage sur chaque face plate étant défini par un premier angle de tressage ¾ et un premier coefficient de remplissage KrL, le motif de tressage sur chaque tranche étant défini par un deuxième angle de tressage ae et un deuxième coefficient de remplissage Kre, le premier angle de tressage ŒL étant choisi pour être compris entre environ 40° et 45°, le deuxième coefficient de remplissage Kre étant choisi pour être d'environ égal à 1 et les autres paramètres du blindage tressé découlant des équations suivantes; This allows the electrical harness to be routed through thin areas while ensuring electromagnetic compatibility between the harness and the equipment within the engine and protection against external attacks (strong fields and lightning). The invention also relates to a method of manufacturing a flat harness intended to transmit electrical signals, comprising the use of a braiding machine to form a braided shield delimited by almost flattened faces comprising two flat faces of predetermined width and two slices of predetermined thickness, each of said faces comprising a braiding pattern different from those of the two adjacent faces, the braiding pattern on each flat face being defined by a first braiding angle ¾ and a first filling coefficient K rL , the braiding pattern on each slice being defined by a second braiding angle a e and a second filling coefficient K re , the first braiding angle ŒL being chosen to be between about 40 ° and 45 °, the second filling coefficient K re being chosen to be approximately equal to 1 and the other parameters of the braided shield deriving from the following equations;
Lm tan(cre) = em tan(aL) et KrL cos (aL) = Kre cos (ae) configurant ainsi les premier et deuxième angles de tressage ainsi que les premier et deuxième coefficients de remplissage pour que les impédances de transfert partielles relatives aux faces plates du blindage tressé soient au moins partiellement en opposition de phase par rapport aux impédances de transfert partielles relatives aux tranches du blindage tressé. L m tan (cr e ) = e m tan (a L ) and K rL cos (a L ) = K re cos (a e ) thus configuring the first and second braiding angles as well as the first and second filling coefficients for that the partial transfer impedances relating to the flat faces of the braided shielding are at least partially in phase opposition with respect to the partial transfer impedances relating to the edges of the braided shielding.
Selon un aspect de la présente invention, on utilise un nombre déterminé de bobines choisi parmi les nombres de bobines suivants : 16, 24, 32, 48, et 64. According to one aspect of the present invention, a determined number of coils is used, chosen from the following numbers of coils: 16, 24, 32, 48, and 64.
Selon un autre aspect de la présente invention, on utilise un nombre de brins par fuseaux compris entre 3 et 16. En outre, le diamètre des brins peut être sélectionné parmi les diamètres suivants : 0,08 mm, 0,10 mm, 0,127 mm, 0,15 mm, et 0,20 mm. According to another aspect of the present invention, a number of strands per spindle of between 3 and 16 is used. In addition, the diameter of the strands can be selected from the following diameters: 0.08 mm, 0.10 mm, 0.127 mm , 0.15 mm, and 0.20 mm.
Brève description des figures Brief description of the figures
[Fig. IA] [Fig. IA]
[Fig. IB] [Fig. IB]
[Fig. IC] [Fig. IC]
[Fig. IDj illustrent de manière schématique un blindage tressé d'un harnais plat, selon un mode de réalisation de l'invention ; [Fig. IDj schematically illustrate a braided shielding of a flat harness, according to one embodiment of the invention;
[Fig. 2] illustre de manière très schématique un procédé de tressage sur un harnais plat, selon un mode de réalisation de l'invention ; [Fig, 3] est un graphe représentant la mise à plat d'un des brins de la tresse sur une longueur d'un pas, selon le procédé de la Fig. 2 ; [Fig. 2] very schematically illustrates a method of braiding on a flat harness, according to one embodiment of the invention; [Fig, 3] is a graph representing the flattening of one of the strands of the braid over a length of one step, according to the method of FIG. 2;
[Fig. 4] et [Fig. 4] and
[Fig. 5] sont des graphes illustrant des relations entre des angles de tressage et un coefficient de remplissage, selon la présente invention ; [Fig. 5] are graphs illustrating relationships between braiding angles and a fill coefficient, according to the present invention;
[Fig. 6] est un graphe représentant la relation entre la phase de l'impédance de transfert et le coefficient de remplissage du blindage tressé ainsi que l'angle de tressage, selon l'invention ; [Fig. 6] is a graph representing the relationship between the phase of the transfer impedance and the filling coefficient of the braided shielding as well as the braiding angle, according to the invention;
[Fig. 7] est un graphe représentant des première et deuxième impédances de transferts dans un plan complexe, relatives respectivement à une face plate et une tranche du blindage tressé rectangulaire, selon l'invention ; [Fig. 7] is a graph representing first and second transfer impedances in a complex plane, relating respectively to a flat face and a slice of the rectangular braided shielding, according to the invention;
[Fig. 8] est un graphe illustrant l'impédance de transfert d'un blindage tressé selon un mode de réalisation préféré de l’invention ; et [Fig. 8] is a graph illustrating the transfer impedance of a braided shield according to a preferred embodiment of the invention; and
[Fig. 9] est un graphe illustrant l'impédance de transfert d’un blindage tressé, selon une technique de tressage de l'état de l'art. [Fig. 9] is a graph illustrating the transfer impedance of a braided shield, according to a braiding technique of the state of the art.
Description des modes de réalisation Description of embodiments
Le concept à la base de l'invention consiste à réaliser un blindage tressé sur un harnais plat en tirant avantage de manière appropriée de la dissymétrie des motifs lors du tressage pour réduire l'impédance de transfert globale du blindage. The concept underlying the invention consists in producing a braided shield on a flat harness by appropriately taking advantage of the asymmetry of the patterns during the braiding to reduce the overall transfer impedance of the shield.
La présente invention s'applique de manière générale à tout type de harnais plats et en particulier pour ceux pouvant être utilisés dans des domaines à haute exigence de sécurité comme par exemple dans le domaine aéronautique. The present invention applies generally to any type of flat harness and in particular to those which can be used in fields with high safety requirements such as for example in the aeronautical field.
Les Figs. IA - 1D illustrent de manière très schématique un blindage tressé d’un harnais plat selon un mode de réalisation de l'invention. Par souci de simplification et de clarté, les schémas ne sont pas représentés à l'échelle. Figs. IA - 1D very schematically illustrate a braided shield of a flat harness according to one embodiment of the invention. For simplicity and clarity, the diagrams are not shown to scale.
Le harnais plat 1 comporte un blindage tressé 3 métallique délimité par des faces quasi aplaties 31, 33 dont chacune comporte un motif de tressage élémentaire 35, 37 différent de ceux des deux faces adjacentes. On entend par « faces quasi aplaties» des faces extrinsèquement planes ou extrinsèquement arquées selon une faible courbure. Ainsi, le harnais plat peut être de forme elliptique aplatie, ovoïdale aplatie, ou quasi rectangulaire aplatie, Les faces du harnais plat peuvent ainsi ne pas être délimitées par des arrêtes franches ou marquées. The flat harness 1 comprises a braided metallic shielding 3 delimited by quasi-flattened faces 31, 33 each of which comprises an elementary braiding pattern 35, 37 different from those of the two adjacent faces. The expression “quasi-flattened faces” is understood to mean faces that are extrinsically flat or extrinsically arcuate in a slight curvature. Thus, the flat harness may be of flattened elliptical, flattened ovoidal, or almost flattened rectangular shape. The faces of the flat harness may thus not be delimited by sharp or marked edges.
Selon ce mode de réalisation, le harnais 1 comporte quatre faces (représentées sur le dessin de manière quasi rectangulaires) et les différents motifs de tressage 35, 37 sont configurés pour que le blindage tressé présente une impédance de transfert minimale. According to this embodiment, the harness 1 has four faces (shown in the drawing in an almost rectangular manner) and the different braiding patterns 35, 37 are configured so that the braided shield has a minimum transfer impedance.
Avantageusement, les faces du harnais plat délimitant le blindage tressé 3 comportent deux faces plates 31 de largeur prédéterminée et deux tranches 33 d’épaisseur prédéterminée. Le rapport entre l'épaisseur e du harnais 1 et sa largeur L, dit facteur de forme, est avantageusement compris entre environ 1 et 1/6 et de préférence entre ½ et ¾. Les faces plates 31 présentent un premier motif de tressage 35 tandis que les tranches 33 présentent un deuxième motif de tressage 37 différent du premier motif 35, Advantageously, the faces of the flat harness delimiting the braided armor 3 comprise two flat faces 31 of predetermined width and two slices 33 of predetermined thickness. The ratio between the thickness e of the harness 1 and its width L, called the form factor, is advantageously between approximately 1 and 1/6 and preferably between ½ and ¾. The flat faces 31 have a first braiding pattern 35 while the slices 33 have a second braiding pattern 37 different from the first pattern 35,
La performance électromagnétique du blindage tressé 3 est donnée par son impédance de transfer qui peut être évaluée à partir des caractéristiques géométriques et matérielles du blindage. Ces caractéristiques comportent le nombre m de bobines ou fuseaux 38 utilisés pour réaliser le tressage, le nombre n de brins élémentaires 39 par fuseau 38, le diamètre d d’un brin élémentaire 39, l'angle de tressage a par rapport à l’axe 11 du harnais 1 ou le pas p (voir également la Fig, 2), et la résistivité p du matériau utilisé pour les brins 39, The electromagnetic performance of the braided shield 3 is given by its transfer impedance which can be evaluated from the geometric and material characteristics of the shield. These characteristics include the number m of coils or spindles 38 used to carry out the braiding, the number n of elementary strands 39 per spindle 38, the diameter d of an elementary strand 39, the braiding angle a with respect to the axis 11 of the harness 1 or the pitch p (see also Fig, 2), and the resistivity p of the material used for the strands 39,
Les Figs, IC et 1D illustrent de manière très schématique une section d'un harnais plat, selon un mode de réalisation de l'invention, Figs, IC and 1D very schematically illustrate a section of a flat harness, according to one embodiment of the invention,
Plus particulièrement, la Fig, IC montre la section d'un harnais pla comportant six câbles 35 placés côte à côte. Les câbles 35 ont tous un même rayon R, Dans ce cas, la largeur L des faces plates 31 est de l'ordre de 6*2*R et l'épaisseur e du harnais 1 est de l’ordre de 2* R. Le facteur de forme (i.e, le rapport entre l’épaisseur e du harnais 1 et sa largeur L) est alors de l'ordre de 1/6, Par ailleurs, les tranches 33 sont arquées selon un rayon de courbure supérieur ou égale à R. More particularly, FIG, IC shows the section of a harness pla comprising six cables 35 placed side by side. The cables 35 all have the same radius R, In this case, the width L of the flat faces 31 is of the order of 6 * 2 * R and the thickness e of the harness 1 is of the order of 2 * R. The form factor (ie, the ratio between the thickness e of the harness 1 and its width L) is then of the order of 1/6. Moreover, the edges 33 are arched according to a radius of curvature greater than or equal to R.
La Fig. 1D montre la section d’un harnais plat comportant douze câbles 35 placés côte à côte sur deux niveaux, Chaque niveau comporte six câbles 35 de même rayon R. Dans ce cas la largeur L des faces plates 31 est toujours de l'ordre de 12R tandis que l'épaisseur e des tranches 33 est de l'ordre de 4R, Le facteur de forme est alors de l'ordre de 1/3 et les tranches 33 sont moins courbées que dans l'exemple de la Fig. IC. Fig. 1D shows the section of a flat harness comprising twelve cables 35 placed side by side on two levels, Each level comprises six cables 35 of the same radius R. In this case the width L of the flat faces 31 is always of the order of 12R while the thickness e of the slices 33 is of the order of 4R. The form factor is then of the order of 1/3 and the slices 33 are less curved than in the example of FIG. IC.
La Fig, 2 illustre de manière très schématique un procédé de tressage sur un harnais plat selon un mode de réalisation de l'invention. FIG, 2 very schematically illustrates a method of braiding on a flat harness according to one embodiment of the invention.
Le blindage tressé 3 est réalisé en utilisant une tresseuse 5 dans laquelle des bobines 51 sont munies chacune de brins élémentaires 39 métalliques (par exemple, en cuivre) assemblés en fuseau. Ces bobines 51 effectuent plusieurs rotations sur un plateau tournant 53 et délivrent des faisceaux de brins 39 métalliques, Par souci de simplification, seuis quatre brins 39 individuels délivrés respectivement par quatre bobines 51 sont représentés sur la Fig, 2. On notera que selon le type de blindage tressé, le nombre de bobines peut être égal à 16, 24, 32, 48, 64, etc., Ce nombre est pair car la moitié des bobines 51 tournent dans un sens pendant que l'autre moitié tourne dans le sens opposé afin que les croisements des brins 39 forment les intersections des tressages. Par ailleurs, le nombre de brins par fuseaux peut être compris entre 3 et 16. En outre, le diamètre d’un brin 39 peut être égal à 0,08 mm, 0,10 mm, 0,127 mm, 0,15 mm, ou 0,20 mm. The braided shielding 3 is produced using a braiding machine 5 in which the coils 51 are each provided with elementary metallic strands 39 (for example, copper) assembled in a spindle. These coils 51 perform several rotations on a turntable 53 and deliver bundles of metal strands 39, For the sake of simplification, only four individual strands 39 delivered respectively by four coils 51 are shown in FIG, 2. It will be noted that depending on the type of braided shield, the number of coils can be 16, 24, 32, 48, 64, etc., This number is even because half of the coils 51 rotate in one direction while the other half rotate in the opposite direction so that the crossings of the strands 39 form the intersections of the braids. On the other hand, the number of strands per spindle can be between 3 and 16. Furthermore, the diameter of a strand 39 can be equal to 0.08 mm, 0.10 mm, 0.127 mm, 0.15 mm, or 0.20 mm.
Contrairement au cas d’un harnais rond, lors du tressage d'un harnais plat 1, la forme du chemin parcouru par les bobines 51 n’est pas la même que la forme du harnais 1, Ceci entraîne une dissymétrie dans le motif de tressage réalisé sauf dans le cas d'un harnais de section carrée. Unlike the case of a round harness, when braiding a flat harness 1, the shape of the path traveled by the coils 51 is not the same as the shape of the harness 1, This results in an asymmetry in the braiding pattern performed except in the case of a square section harness.
Lorsque le harnais 1 est suffisamment petit par rapport au plateau de rotation 53 des bobines 51, un quart de tour de bobine va correspondre à un quart de pas p/4 comme le montre l’exemple de la Fig. 2. On notera qu'un pas p de tressage est défini par un tour complet d’un fuseau ou d'un brin 39 autour du harnais 1. Le pas p correspond donc également à une rotation complète d'une bobine 51 dans la machine de tressage 5. When the harness 1 is sufficiently small compared to the rotation plate 53 of the coils 51, a quarter turn of the coil will correspond to a quarter of a pitch p / 4 as shown in the example of FIG. 2. It will be noted that a braiding pitch p is defined by a complete turn of a spindle or of a strand 39 around the harness 1. The pitch p therefore also corresponds to a complete rotation of a coil 51 in the machine braiding 5.
Lorsque le harnais plat 1 n'est pas de section carré, alors la différence de grandeur entre la largeur L et l'épaisseur e du harnais 1 produit un angle de tressage sur les faces plates 31 diffèrent de celui sur les tranches 33 du harnais 3. When the flat harness 1 is not of square section, then the difference in size between the width L and the thickness e of the harness 1 produces a braiding angle on the flat faces 31 that differs from that on the edges 33 of the harness 3 .
En effet, la Fig. 3 est un graphe représentant la mise à plat d'un des brins de la tresse sur une longueur d'un pas, selon le procédé de la Fig. 2, Le périmètre du harnais plat 1 est représenté en abscisse et la longueur d'un pas p est représentée en ordonnée. Etant donné que le harnais 1 est suffisamment petit par rapport au plateau 53 des bobines 51, le brin 39 fait environ un quart de pas « p/4 » sur la face plate 31 et environ un quart de pas « p/4 » sur la tranche 33 du harnais plat 1. En outre, étant donné que l'épaisseur moyenne e est plus petite que la largeur moyenne Lm du blindage tressé 3, on en déduit que l'angle de tressage a.s sur la tranche 33 d'épaisseur moyenne em est plus faible que l'angle de tressage ai. sur la face plate 31 de largeur moyenne Lm. Plus particulièrement, ces angles de tressage ae et ai. sont liés par l'équation suivante ;
Figure imgf000011_0001
Indeed, FIG. 3 is a graph representing the flattening of one of the strands of the braid over a length of one step, according to the method of FIG. 2, The perimeter of the flat harness 1 is shown on the abscissa and the length of a pitch p is shown on the ordinate. Since the harness 1 is sufficiently small compared to the plate 53 of the coils 51, the strand 39 makes approximately a quarter of a pitch “p / 4” on the flat face 31 and approximately a quarter of a pitch “p / 4” on the slice 33 of the flat harness 1. In addition, given that the average thickness e is smaller than the average width L m of the braided shield 3, it is deduced from this that the braiding angle a. s on the wafer 33 of average thickness e m is smaller than the braiding angle ai . on the flat face 31 of average width L m . More particularly, these braiding angles a e and ai . are related by the following equation;
Figure imgf000011_0001
La largeur moyenne L et l'épaisseur moyenne em du blindage tressé 3 sont respectivement égales à la largeur L et l'épaisseur e du harnais plat 1 augmenté chacune de deux fois le diamètre d d'un brin élémentaire 39 (voir Figs. IA, IB) : The average width L and the average thickness e m of the braided armor 3 are respectively equal to the width L and the thickness e of the flat harness 1 each increased by twice the diameter d of an elementary strand 39 (see Figs. IA , IB):
f f
m L + 2d ; em— e + 2 d {1} m L + 2d; e m - e + 2 d {1}
On notera que l'impédance de transfert Z du blindage tressé 3 est constituée d’une composante résistive Rt et d’une composante inductive Lt. La composante résistive Rt traduit la résistance électrique des brins 39 de la tresse à laquelle se superpose le phénomène de diffusion. Elle peut être définie comme la somme de deux fois ia composante résistive sur la face plate 31 et de deux fois la composante résistive sur ia tranche 33. On peut alors la calculer en effectuant la moyenne de la composante résistive Rti. d'un tressage rond possédant les caractéristiques de la face plate 31 et de la composante résistive Rte d'un tressage rond possédant les caractéristiques de la tranche 33. On obtient alors :
Figure imgf000011_0002
It will be noted that the transfer impedance Z of the braided shield 3 consists of a resistive component R t and of an inductive component L t . The resistive component R t reflects the electrical resistance of the strands 39 of the braid on which the diffusion phenomenon is superimposed. It can be defined as the sum of twice the resistive component on the flat face 31 and twice the resistive component on the wafer 33. It can then be calculated by taking the average of the resistive component R ti. of a round braiding having the characteristics of the flat face 31 and of the resistive component R te of a round braiding having the characteristics of the edge 33. We then obtain:
Figure imgf000011_0002
En outre, la composante inductive Lt dépend des angles de tressage et peut être définie comme la moyenne des composantes inductives LtL et Lte sur les tranches 33 et faces plates 31 du blindage tressé 3. On notera par ailleurs que le nombre de motif de base 35 est identique au nombre de motif de base 37 sur les différentes faces 31, 33 du blindage tressé 3, et comme l'inductance est pondérée par le nombre de motifs de base, alors la composante inductive U est définie par :
Figure imgf000012_0001
In addition, the inductive component L t depends on the braiding angles and can be defined as the average of the inductive components L tL and L te on the edges 33 and flat faces 31 of the braided shield 3. It will also be noted that the number of patterns base 35 is identical to the number of base patterns 37 on the different faces 31, 33 of the braided shielding 3, and as the inductance is weighted by the number of base patterns, then the inductive component U is defined by:
Figure imgf000012_0001
Les équations ci-dessus montrent que l'impédance de transfert Z du blindage tressé 3 dépend des angles de tressages ae et i et ces derniers sont déterminés (selon l'équation (1)) par la géométrie du harnais plat 1. Néanmoins, si on applique un tressage classique sur le harnais plat 1 selon des angles de tressages ae et ai. imposés par les contraintes mécaniques et géométriques du harnais 1, on aura une protection électromagnétique insuffisante dans la plupart des cas comme illustré sur la Fig, 9. The above equations show that the transfer impedance Z of the braided shield 3 depends on the braiding angles a e and i and the latter are determined (according to equation (1)) by the geometry of the flat harness 1. However, if a conventional braiding is applied to the flat harness 1 at braiding angles a e and ai . imposed by the mechanical and geometric constraints of the harness 1, there will be insufficient electromagnetic protection in most cases as illustrated in Fig, 9.
La présente invention résout ce problème en configurant les motifs de tressage 35, 37 sur les tranches 33 et faces plates 31 du blindage tressé 3 pour que ce dernier puisse présenter une impédance de transfert minimale. Cette modulation des motifs de tressage 35, 37 est réalisée en variant les angles de tressage en fonction des coefficients de remplissage sur chacune des faces 31, 33 du blindage tressé 3. Le coefficient de remplissage K (ou de recouvrement) représente le rapport entre la surface couverte par le matériau de ia tresse (Le, les brins) et ia surface totale en ne considérant uniquement les brins placés dans le même sens de rotation autour du harnais. Ce coefficient de remplissage peut être exprimé en pourcentage. A noter que ce coefficient de recouvrement est différent du coefficient de couverture optique qui lui prend en compte la totalité des brins placés dans les deux sens. Ce dernier est donc supérieur au coefficient de recouvrement, The present invention solves this problem by configuring the braiding patterns 35, 37 on the slices 33 and flat faces 31 of the braided shield 3 so that the latter can have a minimum transfer impedance. This modulation of the braiding patterns 35, 37 is achieved by varying the braiding angles as a function of the filling coefficients on each of the faces 31, 33 of the braided shield 3. The filling coefficient K (or covering) represents the ratio between the area covered by the material of the braid (Le, the strands) and the total area considering only the strands placed in the same direction of rotation around the harness. This load factor can be expressed as a percentage. Note that this coverage coefficient is different from the optical coverage coefficient which takes into account all the strands placed in both directions. The latter is therefore greater than the recovery coefficient,
Etant donné que le brin 39 fait environ un quart de pas sur la face plate 31 et environ un quart de pas sur la tranche 33 du harnais 1, l'angle de tressage as sur une tranche 33 et l'angle de tressage CÎL sur une face plate 31 sont reliés au coefficient de remplissage Kre sur une tranche 33 et au coefficient de remplissage Kri. sur une face plate 31 selon l'équation suivante :
Figure imgf000012_0002
Les dimensions du harnais plat 1 et le diamètre d'un brin 39 du blindage tressé 3 étant imposées, on se trouve dans une situation avec quatre paramètres liés par les équations (1), (2) et (5). Ces paramètres sont constitués d'un premier angle <¾ de tressage et d'un premier coefficient de remplissage Kri sur la face plate 31 du harnais plat 1, ainsi qu'un deuxième angle a.s de tressage et un deuxième coefficient de remplissage Kre sur la tranche 33 du harnais plat 1. Since the strand 39 takes about a quarter of a step on the flat face 31 and about a quarter of a step on the edge 33 of the harness 1, the braiding angle a s on a slice 33 and the braiding angle CII on a flat face 31 are connected to the filling coefficient K re on a wafer 33 and to the filling coefficient Kri. on a flat face 31 according to the following equation:
Figure imgf000012_0002
The dimensions of the flat harness 1 and the diameter of a strand 39 of the braided shield 3 being imposed, we find ourselves in a situation with four parameters linked by equations (1), (2) and (5). These parameters consist of a first braiding angle <¾ and a first filling coefficient K ri on the flat face 31 of the flat harness 1, as well as a second angle α. s of braiding and a second filling coefficient K re on the edge 33 of the flat harness 1.
Conformément à l'invention, les premier ¾ et deuxième ae angles de tressage ainsi que les premier KrL et deuxième Kre coefficients de remplissage sont déterminés pour que les impédances de transfert partielles relatives aux faces plates 31 du harnais 1 soient au moins partiellement en opposition de phase par rapport aux impédances de transfert partielles relatives aux tranches 33 du harnais 1, Avantageusement, l'opposition de phase entre les impédances de transfert partielles relatives aux faces plates (31) et les impédances de transfert partielles relatives aux tranches (33) est réalisée dans une bande de fréquence d'intérêt prédéterminée (voir Fig. 9). According to the invention, the first ¾ and second a e braiding angles as well as the first K rL and second K re filling coefficients are determined so that the partial transfer impedances relating to the flat faces 31 of the harness 1 are at least partially in phase opposition with respect to the partial transfer impedances relating to the sections 33 of the harness 1, Advantageously, the phase opposition between the partial transfer impedances relating to the flat faces (31) and the partial transfer impedances relating to the sections (33 ) is performed in a predetermined frequency band of interest (see Fig. 9).
Un mode de réalisation préféré de l'invention consiste à fixer les grandeurs de deux paramètres et à faire varier les autres paramètres de manière à minimiser l'impédance de transfert. Avantageusement, on choisit les deux paramètres les plus appropriés à être fixés en fonction des relations entre les différents paramètres. A preferred embodiment of the invention consists in fixing the magnitudes of two parameters and in varying the other parameters so as to minimize the transfer impedance. Advantageously, the two most appropriate parameters to be set are chosen as a function of the relationships between the various parameters.
En effet, les Figs. 4 et 5 sont des graphes illustrant des relations entre angles de tressage et coefficient de remplissage selon différentes formes du harnais. Indeed, Figs. 4 and 5 are graphs illustrating the relationships between braiding angles and filling coefficient according to different shapes of the harness.
Plus particulièrement, la Fig. 4 illustre la relation entre l'angle ae de tressage sur une tranche 33 et l’angle ai. de tressage sur une face plate 31 selon différents facteurs de forme F1-F4 du harnais plat 1. More particularly, FIG. 4 illustrates the relationship between the angle a e of braiding on a wafer 33 and the angle a i . braiding on a flat face 31 according to different form factors F1-F4 of the flat harness 1.
Pour des raisons de compromis en termes de performance et de masse, l’angle de tressage ¾ sur la face plate 31 du harnais 1 est limité entre 20° et 45°. En effet, au-delà de 45°, le tressage devient dense et le poids du blindage tressé 3 augmente pour une performance basse fréquence plus faible. En revanche, pour des angles plus petits que 20°, on aura une moins bonne tenue mécanique. For reasons of compromise in terms of performance and mass, the braiding angle ¾ on the flat face 31 of the harness 1 is limited to between 20 ° and 45 °. Indeed, beyond 45 °, the braiding becomes dense and the weight of the braided shielding 3 increases for a lower low frequency performance. On the other hand, for angles smaller than 20 °, there will be less good mechanical strength.
Cette figure montre que la croissance de l'angle ae de tressage sur une tranche 33 est lente par rapport à l'augmentation de l'angle de tressage i sur une face plate 33 pratiquement pour tous les facteurs de forme du harnais plat 1, Toutefois,, on constate que l'angle de tressage ae sur la tranche 33 du blindage tressé 3 augmente plus rapidement lorsque l'angle de tressage ai sur la face plate 31 du blindage tressé 3 est entre environ 40° et 45°. This figure shows that the growth of the braiding angle a e on a wafer 33 is slow compared to the increase in the braiding angle i on a substantially flat face 33 for all the form factors of the flat harness 1, however , it is found that the braiding angle a e on the edge 33 of the braided shield 3 increases more rapidly when the braiding angle a on the flat face 31 of the braided shield 3 is between about 40 ° and 45 °.
Par ailleurs, la Fig. 5 illustre la relation entre le coefficient de remplissage Kri et l'angle de tressage ai sur une face plate 31 selon différents facteurs de forme F1-F4 du harnais plat 1 pour une valeur de Kre égale à 1. Moreover, FIG. 5 illustrates the relationship between the filling coefficient K ri and the braiding angle ai on a flat face 31 according to different form factors F1-F4 of the flat harness 1 for a value of Kre equal to 1.
Cette figure montre clairement que la croissance du coefficient de remplissage Kri sur une face plate 31 est très lente par rapport à l'augmentation de l'angle de tressage ai sur cette face pour tous les facteurs de forme du harnais plat 1. This figure clearly shows that the growth of the filling coefficient K ri on a flat face 31 is very slow compared to the increase in the braiding angle ai on this face for all the form factors of the flat harness 1.
On constate alors que, quel que soit le facteur de forme du harnais plat 1, l'angle ae et le coefficient de remplissage Kri sont de faible valeur. Les valeurs maximales de ae et K sont atteintes lorsque ai est proche de 45°. It is then observed that, whatever the form factor of the flat harness 1, the angle a e and the filling coefficient K ri are of low value. The maximum values of a e and K are reached when ai is close to 45 °.
Ainsi, il est avantageux de fixer les valeurs de l'angle de tressage ai sur la face plate 31 ainsi que le coefficient de remplissage Kre sur la tranche 33 du harnais pla 1 pour que la somme des impédances de transfert partielles des face plate 31 et tranche 33 du harnais plat 1 soit plus petite que la valeur de chacune desdites impédances de transfert partielles prises individuellement et par conséquent, en opposition de phase. Thus, it is advantageous to set the values of the braiding angle ai on the flat face 31 as well as the filling coefficient K re on the edge 33 of the harness pla 1 so that the sum of the partial transfer impedances of the flat faces 31 and slice 33 of the flat harness 1 is smaller than the value of each of said partial transfer impedances taken individually and therefore in phase opposition.
L'angle de tressage ai sur la face plate 31 du harnais plat 1 est avantageusement sélectionné entre environ 40° et 45° et de préférence plus proche de 45°. En outre, le deuxième coefficient de remplissage Krs sur la tranche 33 du harnais 1 est choisi pour être proche de l'unité. Ce coefficient de remplissage proche de Ί' peut être obtenu en jouant sur le diamètre des brins 39, le nombre de brins par fuseau 38 et ie nombre de fuseaux. Ceci permet d’après les équations ci-dessus d'avoir un coefficient de remplissage optimal d’environ 0,6 sur les faces plates. En effet, étant donné que chaque face du blindage tressé 3 présente ie même nombre de motifs 35 ou 37, les motifs sur la tranche 33 sont plus serrés que ceux sur la face plate 31 et par conséquent, la valeur du coefficient de remplissage Kre sur la tranche 33 du blindage tressé 3 est plus élevée que celle du coefficient de remplissage KrL sur la face plate 31 d’où l'intérêt de choisir la valeur de Krs le plus proche possible de la valeur 1 (i.e dans un intervalle entre 0,9 et 1), Une fois que les deux grandeurs QL et Kre sont fixées, les autres paramètres du blindage tressé 3 découlent des équations (1), (2) et (6) permettant d'obtenir des impédances de transfert de phases opposées. The braiding angle α1 on the flat face 31 of the flat harness 1 is advantageously selected between approximately 40 ° and 45 ° and preferably closer to 45 °. In addition, the second filling coefficient K rs on the edge 33 of the harness 1 is chosen to be close to unity. This filling coefficient close to Ί 'can be obtained by adjusting the diameter of the strands 39, the number of strands per spindle 38 and the number of spindles. This makes it possible according to the above equations to have an optimum filling coefficient of about 0.6 on the flat faces. In fact, given that each face of the braided shield 3 has the same number of patterns 35 or 37, the patterns on the edge 33 are tighter than those on the flat face 31 and consequently, the value of the filling coefficient K re on the edge 33 of the braided shielding 3 is higher than that of the filling coefficient Kr L on the flat face 31, hence the advantage of choosing the value of K rs as close as possible to the value 1 (ie in an interval between 0.9 and 1), Once the two quantities QL and K re are fixed, the other parameters of the braided shield 3 follow from equations (1), (2) and (6) making it possible to obtain transfer impedances of opposite phases.
En effet, la Fig. 6 est un graphe représentant la relation entre la phase de l'impédance de transfert et le coefficient de remplissage du blindage tressé ainsi que l'angle de tressage. Le coefficient de remplissage K est représenté en ordonnée entre les valeurs 0,3 et 1. La valeur 1 indique que l'espace du harnais 1 est entièrement couvert par les brins 39 d'un même sens de rotation. L’angle de tressage a sur une face du blindage tressé 3 est représenté en abscisse entre les valeurs 15° et 70°. Indeed, FIG. 6 is a graph showing the relationship between the phase of the transfer impedance and the fill coefficient of the braided shield as well as the braiding angle. The filling coefficient K is represented on the ordinate between the values 0.3 and 1. The value 1 indicates that the space of the harness 1 is entirely covered by the strands 39 of the same direction of rotation. The braiding angle a on one side of the braided shield 3 is shown on the abscissa between the values 15 ° and 70 °.
Le graphe est subdivisé en plusieurs régions selon la valeur de la phase f de l'impédance de transfert Z. Ce graphe montre qu'un choix judicieux des configurations du blindage tressé 3 permet d'obtenir deux motifs de tressage 35, 37 dont les impédances de transfert ont des phases opposées. En particulier, ce graphe montre que pour un angle de tressage Q dans une zone B1 entre 40° et 45°, on obtient un coefficient de remplissage Krt autour de 0,6 (i.e. entre 0,5 et 0,7) et une phase fi égale à 90° de la première impédance de transfert Zi (i.e. impédance de transfert partielle sur la face plate 31). En outre, pour un coefficient de remplissage Kra proche de 1, on peut avoir un angle de tressage «¾ dans une zone B2 entre 20° et 35° et une phase cpe à -135° de la deuxième impédance de transfert Ze (i.e. impédance de transfert partielle sur la tranche 33). The graph is subdivided into several regions according to the value of the phase f of the transfer impedance Z. This graph shows that a judicious choice of the configurations of the braided shielding 3 makes it possible to obtain two braiding patterns 35, 37, of which the impedances transfer have opposite phases. In particular, this graph shows that for a braiding angle Q in a zone B1 between 40 ° and 45 °, we obtain a filling coefficient K rt around 0.6 (ie between 0.5 and 0.7) and a phase fi equal to 90 ° of the first transfer impedance Zi (ie partial transfer impedance on the flat face 31). In addition, for a filling coefficient K ra close to 1, we can have a braiding angle "¾ in a zone B2 between 20 ° and 35 ° and a phase cp e at -135 ° of the second transfer impedance Z e (ie partial transfer impedance on section 33).
En effet, la Fig, 7 est un graphe représentant les première et deuxième impédances de transferts ¾ et Ze dans un plan de nombres complexes, relatives respectivement à une face plate et une tranche du blindage tressé rectangulaire, selon l'invention. Indeed, FIG. 7 is a graph representing the first and second transfer impedances ¾ and Z e in a plane of complex numbers, relating respectively to a flat face and a slice of the rectangular braided shielding, according to the invention.
Ce graphe montre que les première et deuxième impédances de transfert partielles Z\ et Zs présentent un déphasage de l'ordre de 225° (i.e. fi - <pe = 90°+135° = 225°). Cette valeur est proche de 180° qui serait le déphasage parfait entre Z· et Ze. Le module Z de la somme des première et deuxième impédances de transferts Zi et Ze est ainsi inférieur au module de chacune des impédances de transfert partielles Zi et Ze prises individuellement. This graph shows that the first and second partial transfer impedances Z \ and Z s have a phase shift of the order of 225 ° (ie fi - <p e = 90 ° + 135 ° = 225 °). This value is close to 180 ° which would be the perfect phase shift between Z · and Z e . The modulus Z of the sum of the first and second transfer impedances Zi and Z e is thus less than the modulus of each of the partial transfer impedances Zi and Z e taken individually.
La Fig. 8 est un graphe illustrant l'impédance de transfert d'un blindage tressé selon un mode de réalisation préféré de l'Invention. Ce graphe est réalisé en mesurant l'impédance de transfert de manière indépendante sur une face plate, sur une tranche et sur le périmètre du blindage tressé sur un harnais plat. Pour mesurer l'impédance de transfert sur une face, on fait circuler un courant entre le blindage et un fil mis au-dessus de la face d'intérêt et on mesure la tension de couplage entre le fil et le blindage selon la technique dite du fil d'injection. En outre, pour mesurer l’impédance de transfert globale, on utilise le même procédé mais, cette fois-ci, sur un fi! mis en spirale autour du périmètre du blindage. Fig. 8 is a graph illustrating the transfer impedance of a braided shield according to a preferred embodiment of the invention. This graph is produced by measuring the transfer impedance independently on a flat face, on a wafer and on the perimeter of the braided shield on a flat harness. To measure the transfer impedance on one side, a current is circulated between the shielding and a wire placed above the side of interest and the coupling voltage between the wire and the shielding is measured using the technique known as injection wire. In addition, to measure the overall transfer impedance, we use the same method but, this time, on a fi! spiraled around the perimeter of the armor.
Le graphe représente le module de l’impédance de transfert selon l'invention en fonction de la fréquence. La courbe Cil représente le module de l'impédance de transfert sur une face plate 31 du blindage tressé 3 tandis que la courbe C12 représente le module de l'impédance sur une tranche 33 du blindage tressé 3. En outre, la courbe C13 représente le module de l'impédance totale du blindage tressé 3. La courbe C13 se situe bien en dessous des courbes Cil et C12 traduisant le fait que les impédances de transfert partielles présentent des phases opposées. Finalement, la courbe S représente le seuil supérieur du module de l’impédance de transfert selon certaines spécifications aéronautiques. Ce graphe montre que la courbe C13 représentant le module de l'impédance globale du blindage tressé est bien en dessous du seuil S des spécifications indiquant par conséquent une très bonne performance électromagnétique. The graph represents the modulus of the transfer impedance according to the invention as a function of frequency. Curve Cil represents the modulus of the transfer impedance on a flat face 31 of the braided shield 3 while the curve C12 represents the modulus of the impedance on a slice 33 of the braided shield 3. In addition, the curve C13 represents the modulus of the total impedance of the braided shield 3. The curve C13 is situated well below the curves C11 and C12, reflecting the fact that the partial transfer impedances have opposite phases. Finally, the S curve represents the upper threshold of the transfer impedance modulus according to certain aeronautical specifications. This graph shows that the curve C13 representing the modulus of the overall impedance of the braided shield is well below the threshold S of the specifications, therefore indicating very good electromagnetic performance.
Ainsi, pour un harnais électrique de forme et de section prédéterminées, la présente invention permet de choisir astucieusement les paramètres du blindage : nombre de fuseaux, nombre de brins par fuseaux, diamètres des brins et un des angles de tressage, de manière à obtenir des Impédances partielles en opposition de phase entre chaque face et une face adjacente. Ceci a pour effet technique de minimiser de manière avantageuse l’impédance globale de transfert du blindage tressé. On notera qu'uniquement deux des quatre paramètres comprenant les angles de tressage et les coefficients de remplissage de deux faces adjacents sont sélectionnés car les deux autres sont imposés par la géométrie et la configuration du harnais plat selon les équations décrites précédemment. On notera qu’une fois ces deux paramètres sélectionnés on choisit la faille des brins, le nombre de brins par fuseaux et le nombre de fuseaux pour se rapproche au maximum de la valeur sélectionné ou imposée par les équations pour ces paramètres. Avantageusement, le harnais plat selon l'invention peut être réalisé sur seulement une partie de la longueur d'un harnais rond. Autrement dit, le harnais électrique peut être rond sur une grande partie de sa longueur puis mis à plat sur certaines portions pour permettre le passage du harnais dans des zones confinées présentant des sections inférieures à la section du harnais rond. Thus, for an electrical harness of predetermined shape and section, the present invention makes it possible to cleverly choose the parameters of the shielding: number of spindles, number of strands per spindle, diameters of the strands and one of the braiding angles, so as to obtain Partial impedances in phase opposition between each face and an adjacent face. This has the technical effect of advantageously minimizing the overall transfer impedance of the braided shield. It will be noted that only two of the four parameters comprising the braiding angles and the filling coefficients of two adjacent faces are selected because the other two are imposed by the geometry and the configuration of the flat harness according to the equations described above. It will be noted that once these two parameters have been selected, the strand fault, the number of strands per spindle and the number of spindles are chosen to approximate as much as possible to the value selected or imposed by the equations for these parameters. Advantageously, the flat harness according to the invention can be produced over only part of the length of a round harness. In other words, the electrical harness can be round over a large part of its length and then flattened over certain portions to allow the harness to pass through confined areas having sections smaller than the section of the round harness.
L'invention vise également un système électrique d'aéronef comportant des harnais ronds partiellement aplaties (i.e. comportant des harnais plats sur certaines portions) ou des harnais plats sur toutes leurs longueurs. The invention also relates to an aircraft electrical system comprising partially flattened round harnesses (i.e. comprising flat harnesses on certain portions) or flat harnesses over all their lengths.

Claims

REVENDICATIO S
1, Harnais plat destiné à transmettre des signaux électriques, caractérisé en ce qu'il comporte un blindage tressé (3) délimité par des faces quasi aplaties (31, 33) comportant deux faces plates (31) de largeur prédéterminée et deux tranches (33) d’épaisseur prédéterminée, chacune desdites faces (31, 33) comportant un motif de tressage (35, 37) différent de ceux des deux faces adjacentes, le motif de tressage (35) sur chaque face plate (31) étant défini par un premier angle de tressage ¾. et un premier coefficient de remplissage Kr le motif de tressage (37) sur chaque tranche (33) étant défini par un deuxième angle de tressage ae et un deuxième coefficient de remplissage Krs, le premier angle de tressage i étant choisi pour être compris entre environ 40° et 45°, le deuxième coefficient de remplissage Krs étant choisi pour être d'environ égal à 1 et les autres paramètres du blindage tressé découlant des équations suivantes: 1, Flat harness for transmitting electrical signals, characterized in that it comprises a braided shield (3) delimited by almost flattened faces (31, 33) comprising two flat faces (31) of predetermined width and two slices (33 ) of predetermined thickness, each of said faces (31, 33) comprising a braiding pattern (35, 37) different from those of the two adjacent faces, the braiding pattern (35) on each flat face (31) being defined by a first braiding angle ¾ . and a first filling coefficient K r the braiding pattern (37) on each wafer (33) being defined by a second braiding angle a e and a second filling coefficient K rs , the first braiding angle i being chosen to be between approximately 40 ° and 45 °, the second filling coefficient K rs being chosen to be approximately equal to 1 and the other parameters of the braided shielding resulting from the following equations:
Lm tan(c?e) = em tan (aL) et KrL eos(cr ) = Kre cos(cre) configurant ainsi ies premier et deuxième angles de tressage ainsi que les premier et deuxième coefficients de remplissage pour que les impédances de transfert partielles relatives aux faces plates (31) du blindage tressé (3) soient au moins partiellement en opposition de phase par rapport aux impédances de transfert partielles relatives aux tranches (33) du blindage tressé (3). L m tan (c? E ) = e m tan (a L ) and K rL eos (cr) = K re cos (cr e ) thus configuring the first and second braiding angles as well as the first and second filling coefficients for that the partial transfer impedances relating to the flat faces (31) of the braided shield (3) are at least partially in phase opposition with respect to the partial transfer impedances relating to the slices (33) of the braided shield (3).
2, Harnais selon la revendication 1, caractérisé en ce que le rapport entre l’épaisseur du harnais et sa largeur, dit facteur de forme, est compris entre environ 1 et 1/6 et de préférence entre ½ et ¾. 2, Harness according to claim 1, characterized in that the ratio between the thickness of the harness and its width, said form factor, is between about 1 and 1/6 and preferably between ½ and ¾.
3, Harnais selon la revendication 1 ou 2, caractérisé en ce que l'angle de tressage sur ia face plate (31) ainsi que le coefficient de remplissage sur la tranche (33) du blindage tressé (3) sont sélectionnés pour que la somme de l’impédance de transfert partielle d’une face plate (31) et l’impédance de transfert partielle d'une tranche (33) du blindage tressé (3) soit plus petite que 1a valeur de chacune desdites impédances de transfert partielles prisent individuellement. 3, Harness according to claim 1 or 2, characterized in that the braiding angle on the flat face (31) as well as the filling coefficient on the edge (33) of the braided shield (3) are selected so that the sum the partial transfer impedance of a flat face (31) and the partial transfer impedance of a slice (33) of the braided shield (3) is smaller than the value of each of said partial transfer impedances taken individually .
4. Harnais selon i'une quelconque des revendications précédentes, caractérisé en ce que le premier angle de tressage est choisi pour être proche de 45°, 4. Harness according to any one of the preceding claims, characterized in that the first braiding angle is chosen to be close to 45 °,
5. Harnais selon i'une quelconque des revendications précédentes, caractérisé en ce que l’opposition de phase entre les impédances de transfert partielles relatives aux faces plates (31) et les impédances de transfert partielles relatives aux tranches (33) est réalisée dans une bande de fréquence d'intérêt prédéterminée. 5. Harness according to any one of the preceding claims, characterized in that the phase opposition between the partial transfer impedances relating to the flat faces (31) and the partial transfer impedances relating to the slices (33) is produced in a predetermined frequency band of interest.
6. Harnais selon l'une quelconque des revendications précédentes, caractérisé en ce que les faces aplaties sont quasiment arquées. 6. Harness according to any one of the preceding claims, characterized in that the flattened faces are almost arched.
7. Harnais électrique caractérisé en ce qu’il comporte au moins une portion plate, dite harnais plat selon l'une quelconque des revendications précédentes. 7. Electrical harness characterized in that it comprises at least one flat portion, called a flat harness according to any one of the preceding claims.
8. Harnais électrique selon la revendication 7, caractérisé en ce qu'il comporte un harnais rond intercalé sur au moins une portion prédéterminée par un harnais plat, ledit harnais plat étant configuré pour passer dans des zones présentant des sections inférieures à la section du harnais rond. 8. Electrical harness according to claim 7, characterized in that it comprises a round harness interposed on at least one predetermined portion by a flat harness, said flat harness being configured to pass through areas having sections smaller than the section of the harness. round.
9. Système électrique d'aéronef comportant au moins un harnais électrique selon la revendication 7 ou 8. 9. An aircraft electrical system comprising at least one electrical harness according to claim 7 or 8.
10. Procédé de fabrication d’un harnais plat destiné à transmettre des signaux électriques, caractérisé en ce qu'il comporte l'utilisation d’une machine à tresser pour former un blindage tressé délimité par des faces quasi aplaties (31, 33) comportant deux faces plates (31) de largeur prédéterminée et deux tranches (33) d'épaisseur prédéterminée, chacune desdites faces (31, 33) comportant un motif de tressage (35, 37) différent de ceux des deux faces adjacentes, le motif de tressage (35) sur chaque face plate (31) étant défini par un premier angle de tressage <¾ et un premier coefficient de remplissage KrL, le motif de tressage (37) sur chaque tranche (33) étant défini par un deuxième angle de tressage ae et un deuxième coefficient de remplissage Kre, le premier angle de tressage i étant choisi pour être compris entre environ 40° et 45°, le deuxième coefficient de remplissage Kre étant choisi pour être d'environ égal à 1 et les autres paramètres du blindage tressé découlant des équations suivantes: 10. A method of manufacturing a flat harness intended to transmit electrical signals, characterized in that it comprises the use of a braiding machine to form a braided shield delimited by almost flattened faces (31, 33) comprising two flat faces (31) of predetermined width and two slices (33) of predetermined thickness, each of said faces (31, 33) comprising a braiding pattern (35, 37) different from those of the two adjacent faces, the braiding pattern (35) on each flat face (31) being defined by a first braiding angle <¾ and a first filling coefficient K rL , the pattern of braiding (37) on each slice (33) being defined by a second braiding angle a e and a second filling coefficient K re , the first braiding angle i being chosen to be between approximately 40 ° and 45 °, the second filling coefficient K re being chosen to be approximately equal to 1 and the other parameters of the braided shielding resulting from the following equations:
Lm tan(ae) = em tan (¾) et KrL cos (¾) = Kre cos(ae) configurant ainsi les premier et deuxième angles de tressage ainsi que les premier et deuxième coefficients de remplissage pour que les impédances de transfert partielles relatives aux faces plates (31) du blindage tressé (3) soient au moins partiellement en opposition de phase par rapport aux impédances de transfert partielles relatives aux tranches (33) du blindage tressé (3). L m tan (a e ) = e m tan (¾) and K rL cos (¾) = K re cos (a e ) thus configuring the first and second braiding angles as well as the first and second filling coefficients so that the Partial transfer impedances relating to the flat faces (31) of the braided shield (3) are at least partially in phase opposition with respect to the partial transfer impedances relating to the slices (33) of the braided shield (3).
11. Procédé selon la revendication 10, caractérisé en ce qu'on utilise un nombre déterminé de bobines choisi parmi les nombre de bobines suivants : 16, 24, 32, 48, et 64. 11. The method of claim 10, characterized in that a determined number of coils chosen from the following number of coils: 16, 24, 32, 48, and 64 is used.
12. Procédé selon la revendication 10, caractérisé en ce qu'on utilise un nombre de brins par fuseaux compris entre 3 et 16 et en ce que le diamètre des brins est sélectionné parmi les diamètres suivants : 0,08 mm, 0,10 mm, 0,127 mm, 0,15 mm, et 0,20 mm. 12. The method of claim 10, characterized in that a number of strands per spindle between 3 and 16 is used and in that the diameter of the strands is selected from the following diameters: 0.08 mm, 0.10 mm , 0.127mm, 0.15mm, and 0.20mm.
PCT/FR2020/050565 2019-03-19 2020-03-16 Braided shield of a flat harness WO2020188215A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1902808 2019-03-19
FR1902808A FR3094130B1 (en) 2019-03-19 2019-03-19 BRAIDED SHIELDING OF A FLAT HARNESS

Publications (1)

Publication Number Publication Date
WO2020188215A1 true WO2020188215A1 (en) 2020-09-24

Family

ID=67514816

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FR2020/050565 WO2020188215A1 (en) 2019-03-19 2020-03-16 Braided shield of a flat harness

Country Status (2)

Country Link
FR (1) FR3094130B1 (en)
WO (1) WO2020188215A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634782A (en) * 1969-10-01 1972-01-11 Thomas & Betts Corp Coaxial flat cable
US4822950A (en) * 1987-11-25 1989-04-18 Schmitt Richard J Nickel/carbon fiber braided shield
US5112419A (en) * 1988-10-12 1992-05-12 Kitagawa Industries Co., Ltd. Method for producting strip cable
WO1996027197A1 (en) 1995-03-02 1996-09-06 Labinal Shielded cable and stranding, and method for making same
US6844500B2 (en) * 2002-01-07 2005-01-18 Conectl Corporation Communications cable and method for making same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3634782A (en) * 1969-10-01 1972-01-11 Thomas & Betts Corp Coaxial flat cable
US4822950A (en) * 1987-11-25 1989-04-18 Schmitt Richard J Nickel/carbon fiber braided shield
US5112419A (en) * 1988-10-12 1992-05-12 Kitagawa Industries Co., Ltd. Method for producting strip cable
WO1996027197A1 (en) 1995-03-02 1996-09-06 Labinal Shielded cable and stranding, and method for making same
US6844500B2 (en) * 2002-01-07 2005-01-18 Conectl Corporation Communications cable and method for making same

Also Published As

Publication number Publication date
FR3094130B1 (en) 2022-12-30
FR3094130A1 (en) 2020-09-25

Similar Documents

Publication Publication Date Title
EP2878064B1 (en) Axial-flow electric motor
EP0886889A1 (en) Wide band printed network antenna
EP2636096B1 (en) Artificial magnetic conductor, and antenna
FR2692404A1 (en) Basic pattern of broadband antenna and antenna-network with it.
EP3729607B1 (en) Stator for electrical rotating machine
FR2862818A1 (en) Stator for dynamoelectric machine e.g. electrical alternator, has stator winding including conductors that define air flow paths that extend via loop segments, between phases of segments, as well as between layers of segments
FR2999355A1 (en) OMNIBUS BAR INTEGRATED TO AN ELECTRIC MOTOR
EP0828305A1 (en) Device for transporting an electric signal protected against electromagnetic disturbances
WO2020188215A1 (en) Braided shield of a flat harness
EP0717420B1 (en) Manufacturing process of a shielding jacket on an electrical conductor harness, and harness obtained by such a process
EP2828931A1 (en) Compact helical antenna with a sinusoidal profile modulating a fractal pattern
CA3124805C (en) Energy recovery device on at least one power conductor and method for manufacturing the recovery device
CA2294109C (en) Two-slot plane coiling method for rotating electric machine
WO2019121979A1 (en) Stator for a rotating electrical machine
FR3075503B1 (en) STATOR FOR ROTATING ELECTRIC MACHINE
EP1642485B1 (en) Electronic device provided with a magnetic screening
WO1996027197A1 (en) Shielded cable and stranding, and method for making same
EP1251581A1 (en) High frequency integrated inductive coil
EP2946458A2 (en) Method for winding a rotor or a stator by partial insertions of phase windings
FR3054740A1 (en) STATOR BODY FOR ROTATING ELECTRICAL MACHINE
EP0990295B2 (en) Coiling method and coils for rotating electric machine
WO2019122608A1 (en) Superconducting current limiting dipole, comprising at least four superconducting cables
FR2816122A1 (en) Rotating electric machine for motor vehicles with the armature slots holding an internal and an external conductor, uses two conductors per slot, with the outer conductor having greater diameter than the inner conductor
WO2021053087A1 (en) Rotary electric machine stator comprising at least one slot insulator
WO2023285754A1 (en) Stator for rotary electric machine and manufacturing method

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20726218

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20726218

Country of ref document: EP

Kind code of ref document: A1